This invention relates to the field of tooth whitening using chewing gum.
Teeth whiteners, also known as teeth bleaching agents, are in widespread use as a cosmetic means to enhance appearance and to contribute to better oral health and hygiene in general.
Among teeth whitening formulations, those containing oxidizing agents as active ingredients are preferred because of their fast action and superior efficacy. The most frequently employed peroxide in teeth whitening materials is hydrogen peroxide, either in free form or as an adduct with urea known as carbamide peroxide.
Prior art devices can be classified in three groups based on the method of delivering the material to tooth surfaces. The first is whitening toothpastes, in which bleaching agents are typically incorporated as an additional feature in toothpaste formulations. Another category contains formulations intended specifically for whitening teeth, usually in gel form, which are typically delivered to the tooth surface by fabricated trays. Such materials may be administered under the control of a dental professional or designed for in-home use. Finally, the newest trend in tooth whitening devices involves chewing gum products.
Chewing gum whitening products offer an attractive alternative to more cumbersome and time intensive whitening systems because they are substantially more user friendly. People find chewing gum pleasurable, and are willing to chew gum for much longer periods of time than they typically wear trays or brush their teeth. Such a method of delivery offers whitening action without sacrifice of time or comfort.
The common shortcoming of most prior art peroxide-based teeth whitening devices, especially those based on hydrogen or carbamide peroxides, is their instability. The efficacy of such materials deteriorates over time, particularly when exposed to elevated temperatures. Chewing gums of the prior art are more vulnerable than other whitening devices to the loss of efficacy upon storage because they require the use of anhydrous peroxides. This makes carbamide peroxide the active ingredient of choice, because it is the most effective of the peroxides of traditional bleaching formulations available in a dry form.
However, carbamide peroxide is particularly prone to accelerated decomposition when in contact with common ingredients of chewing gums (e.g. particulate matter such as calcium bicarbonate, or other alkaline materials). The use of stabilizing additives is therefore counterproductive because incorporation of such materials negatively affects the product""s whitening efficacy. Stability is therefore in direct conflict with the purpose and objective of their applications, namely achieving the best possible whitening effect in a reasonable length of contact with the tooth surface. Since the efficacy of the material is of greater concern, the shelf life of most prior art chewing gum teeth whitening formulations is extremely limited.
Thus, the shortcomings of prior art teeth whitening chewing gum formulations may be summarized as follows:
A) The inherent conflict between the requirements of shelf life stability of peroxides and the understandable demand for fast bleaching action and high efficacy of the product. Formulations which exhibit adequate shelf life, as evidenced by maintaining stable peroxide concentrations over time, are intrinsically less effective due to the slow generation of radical (atomic) oxygen in the oral environment which impairs the speed and efficacy of the teeth bleaching process;
B) The difficulty in formulating chewing gums of adequate shelf life due to the vulnerability of anhydrous peroxides, particularly carbamide peroxide, in the presence of common ingredients of chewing gum formulations.
C) Technical difficulties associated with manufacturing of teeth whitening chewing gums in the form of two parts mixed in the mouth during mastication.
In view of the shortcomings of the prior art, preferred embodiments of the present invention provide a fast acting tooth whitening chewing gum which is virtually insensitive to storage conditions, provides a safe, effective and convenient method for whitening teeth and/or contributes to improved oral health and hygiene. The chewing gum comprises peroxides of the first or second group of the Periodic Table, preferably calcium, zinc and/or strontium, at concentrations corresponding to 1-20% by weight hydrogen peroxide, and anhydrous organic acids, preferably tartaric, citric, lactic, oxalic or mixtures thereof. In one embodiment, the one or more organic acids are at a concentration of 1% to 20% by weight, preferably 8% to 12%. In a further embodiment, the one or more peroxides are at a concentration of 3% to 12% by weight hydrogen peroxide. In one embodiment, the peroxides are calcium peroxide, zinc peroxide, or strontium peroxide. In a further aspect, the pH of a water extract from the chewing gum is between 4 and 11. In a further embodiment, the chewing gum has further hydrophilic additives such as glycerin, propylene glycol, and polyglycols. In a further embodiment, the chewing gum has sweeteners such as xylitol, fructose, sorbitol, sucrose, saccharine, and aspartame. The chewing gum may also contain food grade colorants, flavors, fragrances, and mixtures thereof. Preferably the colorants are FDandC Blue #1 or #2. Preferably the colorants are orange, lemon, peppermint, spearmint, mint, bubble gum, cherry, watermelon, strawberry or apple varieties. The chewing gum may also have fluoride salts, such as sodium fluoride, stannous fluoride, sodium monofluorophosphate, and mixtures thereof.